Upon the advent of critical fuel shortages and especially fuel oil in recent years, considerable attention has been directed to the development of efficient fireplace and stove structures capable of consuming readily replenishable fuel such as wood. Wood has been a common type of fuel for many centuries for heating and cooking purposes but because of the relatively rapid consumption of the wood by conventional fireplaces, the use of substitute fuels over the years such as coal and, more recently, fuel oil, has been resorted to for purposes of heating houses and buildings.
Fossil fuel such as coal and oil are non-replaceable, whereas wood is replaceable and renewable. Because of this property and available supplies of wood, attention has been directed recently to the development of fireplaces and stoves which will utilize wood as a fuel but extend the burning time of the wood so that it will not be consumed as readily as when it is simply burned in an open fireplace, either with or without supplemental means to heat ambient air being included in and around the fireplace or stove structures.
In attempts to improve the combustion of fireplace fuel and especially wood, it has been common practice in recent years to provide perforated tubes connected to exhaust means of power operated fans for purposes of discharging air either as part of a grate or immediately associated with a grate. Examples of devices of this type are illustrated in the following U.S. Pat. Nos: 3,269,383 Maasberg Aug. 30, 1966; 3,942,509 Sasser Mar. 9, 1976; 4,019,492 Rush Apr. 26, 1977.
The structures of the foregoing patents have not included means to minimize the burning of fuel, such as by offsetting the combustion promoted by the forced air such as by utilizing dampers in closed fronts on the fireplaces or stoves by which the combustion occurs at a slower rate.
Basically, the use of hinged doors in the front of fireplace-type stoves has been proposed previously such as in U.S. Pat. Nos. 1,620,235, to Royse, dated Mar. 8, 1927 and U.S. Pat. No. 2,028,088 to Davidson et al, dated Jan. 14, 1936, and in which damper means mounted in the doors for the furnace or fireplace fronts apparently are employed to control the rate of combustion to a certain extent.
Although certain basic principles of efficient operation of fireplace structures are illustrated in various ways in the patents referred to specifically above, as well as other similar patented structures which are somewhat repetitive and duplicates of those discussed, it has been found that relatively inexpensive and highly efficient fireplace-type stove structures can be devised which employ certain modifications of the features presently found in prior structures and utilized and combined in different ways to maximize the efficiency of the fireplace-type stove and particularly to increase the time of burning of renewable fuels, such as wood, particularly logs, not only during daytime use, but particularly during the night when, normally a conventional fireplace will have completely consumed the fuel long before the oncoming day and it is necessary to start a fire again in the fireplace by conventional means.
Such more efficient structures and features are embodied in the present invention, details of which are described hereinafter.